Selective conversion of CO2 to isobutane-enriched C4 alkanes over InZrOx-Beta composite catalyst

Direct conversion of CO2 to a single specific hydrocarbon with high selectivity is extremely attractive but very challenging. Herein, by employing an InZrOx-Beta composite catalyst in the CO2 hydrogenation, a high selectivity of 53.4% to butane is achieved in hydrocarbons (CO free) under 315 °C and 3.0 MPa, at a CO2 conversion of 20.4%. Various characterizations and DFT calculation reveal that the generation of methanol-related intermediates by CO2 hydrogenation is closely related to the surface oxygen vacancies of InZrOx, which can be tuned through modulating the preparation methods. In contrast, the three-dimensional 12-ring channels of H-Beta conduces to forming higher methylbenzenes and methylnaphthalenes containing isopropyl side-chain, which favors the transformation of methanol-related intermediates to butane through alkyl side-chain elimination and subsequent methylation and hydrogenation. Moreover, the catalytic stability of InZrOx-Beta in the CO2 hydrogenation is considerably improved by a surface silica protection strategy which can effectively inhibit the indium migration.


REVIEWER COMMENTS</B>
Reviewer #1 (Remarks to the Author): Selective hydrogenation of CO2 to value-added chemicals such as butane is very challenging, as it involves C-C coupling and modulated carbon-chain growth. In this work, the authors report that InZrOx and H-Beta composite catalysts show a promising butane selectivity of >53% along with a CO selectivity of ~35% at a CO2 conversion of ~20%. In situ DRIFTS, isotope-labeling experiments, and DFT calculations have been combined to elucidate the reaction mechanism and pathways for the production of butane. In addition, phase separation of InZrOx oxide and transfer of indium species to zeolite are interestingly mitigated by grafting a layer of SiO2 on its surface, which not only significantly improves catalytic stability, but also inhibits CO formation. This work is original and highly innovative, and it has made a novel and significant contribution to this emerging area. This paper is well organized and clearly written. I recommend publishing this work after minor revisions.
1. Considering that the catalytic test was performed on reduced samples, the O1s XPS spectra of reduced InZrOx oxide should be provided for estimating the real surface oxygen vacancy concentration in the reaction. 2. Please provide the coking rates of InZrOx(CP)-Beta(40), InZrOx(SCP-4)-Beta and InZrOx(SCP-8)-Beta catalysts in the reaction. 3. The authors should provide structural coordinates for optimized transition states of butane formation.
Reviewer #2 (Remarks to the Author): This manuscript reports the combination of two catalysts, one a modified In oxide promoting CO2 hydrogenation to methanol, and another one a zeolite transforming methanol into butane, to develop a tandem process in which CO2 is hydrogenated selectively to a single hydrocarbon. The topic is of much interest and the results in terms of CO2 conversion and butane selectivity are encouraging. The main novelty is the combination of the two catalysts in a granular blend, since the activity of each of the two catalyst types for each reaction is well known. Publication in Nature Communications is recommended with some changes addressing the following comments: • The title it is confusing, since it does not mention CO that is the major hydrogenation product and butane is formed in much lesser selectivity (in contrast to what the title suggests). I think that isobutane should appear somehow in the title. • Regarding H2-TPR, the reader is wondering why the minor peaks are commented, while the most intense peaks that can start contributing at 315 oC under constant temperature even in a larger extent are neglected.
• The influence of H2O in the process should be addressed by adding various proportions in the feed. • How the zeolite was separated from the InZrOx(CP)-Beta for analysis of the aromatic carbon species should be described in detail in the experimental section.
• The concept of a silica overlayer to avoid In migration to Beta zeolite is interesting, but it does not solve adequately the issue of InZrOx stability. Why does the Si overlayer increase InZrOx stability? Which is the operating mechanism? • It is proposed that the authors use silica-coated InZrOx and determine the relocation of In on the silica layer under reaction conditions over the time on stream. Should it not the In environment change from Zr to Si over the time? Why this change does not affect to the hydrogenation performance of the catalyst? What would be the performance and stability of an InSiOx phase? • Figure S15 and Figs. 16A and 17A should be improved to present more clearly the silica overlayer on InZrOx. Particle size distribution in Fig. S19 is difficult to be seen. • Characterization of the exhaustively used silica-coated InZrOx by XRD and other techniques should be presented. The absence of XRD corresponding to SiO2 does not prove its dispersion, since it could correspond to an amorphous silica phase. • Fig. 8 does not convincingly proves catalyst stability. First the times on stream are similar for the three catalysts having different SiO2 layer. Second, there is a decrease in the butane selectivity at times longer than 80 h, but nothing is commented on this important change.
If the authors address satisfactorily the previous points, publication would be recommended.

Response to the referees for the Manuscript NCOMMS-22-46197
To Reviewer #1: Q0: Selective hydrogenation of CO2 to value-added chemicals such as butane is very challenging, as it involves C-C coupling and modulated carbon-chain growth. In this work, the authors report that InZrOx and H-Beta composite catalysts show a promising butane selectivity of >53% along with a CO selectivity of ~35% at a CO2 conversion of ~20%. In situ DRIFTS, isotope-labeling experiments, and DFT calculations have been combined to elucidate the reaction mechanism and pathways for the production of butane. In addition, phase separation of InZrOx oxide and transfer of indium species to zeolite are interestingly mitigated by grafting a layer of SiO2 on its surface, which not only significantly improves catalytic stability, but also inhibits CO formation. This work is original and highly innovative, and it has made a novel and significant contribution to this emerging area. This paper is well organized and clearly written. I recommend publishing this work after minor revisions.
Response: Thanks to the reviewer for the very positive comments as well as the informative and instructive revision advices. With the help of these advices, the revised manuscript was improved greatly. We are pleased that the reviewer has clearly recognized the novelty and merits of this manuscript and hope that our revision work is satisfactory to the reviewer and the acceptance of this manuscript for publication can be approved.  Supplementary Fig. 6 and addressed in the revised manuscript (Pages 7-8), like: "In addition, the same sequence of three oxides by the surface oxygen vacancy concentration is manifested by the in situ O 1s XPS results ( Supplementary Fig. 6), viz., InZrOx(CP) (43.47%) > InZrOx(SG) (36.75%) > InZrOx(HT) (31.76%). The in situ O 1s XPS gives higher surface oxygen vacancy concentrations than the ex situ one, which is ascribed to the fact that more surface oxygen defects are formed due to the elimination of certain surface oxygen atoms by reduction in the in situ H2-containing atmosphere, in agreement with previous works (Chem. 2022(Chem. , 8, 1376J. Catal. 2022, 413, 923  It should be mentioned that unlike the conversion of methanol to hydrocarbons (MTH) over a zeolite catalyst in the N2 or Ar atmosphere, for the hydrogenation of CO2 to hydrocarbons, the presence of H2 and H2O in high pressure can effectively eliminate the coke precursors and thus greatly hinder the formation and accumulation of coke species. (Nat. Catal. 2018, 1, 666;Nat. Catal. 2022, 5, 1038. As a result, the coke deposition should not be the major cause of catalyst deactivation in the hydrogenation of CO2 to hydrocarbons. Taking the reviewer's concern into account, above points were strengthened in the revised manuscript (Page 28).

Q3: The authors should provide structural coordinates for optimized transition states of butane formation.
Response: Thanks to the reviewer for the valuable suggestion. Following the reviewer's suggestion, the structural coordinates for optimized transition states of butane formation have been provided in the Supplementary Data.

To Reviewer #2:
Q0: This manuscript reports the combination of two catalysts, one a modified In oxide promoting CO2 hydrogenation to methanol, and another one a zeolite transforming methanol into butane, to develop a tandem process in which CO2 is hydrogenated selectively to a single hydrocarbon. The topic is of much interest and the results in terms of CO2 conversion and butane selectivity are encouraging. The main novelty is the combination of the two catalysts in a granular blend, since the activity of each of the two catalyst types for each reaction is well known. Publication in Nature Communications is recommended with some changes addressing the following comments.
Response: Thanks to the reviewer for the very positive comments as well as the informative and instructive revision advices. With the help of these advices, the revised manuscript was improved greatly. We are pleased that the reviewer has clearly recognized the novelty and merits of this manuscript and hope that our revision work is satisfactory to the reviewer and the acceptance of this manuscript for publication can be approved.

Q1:
The title it is confusing, since it does not mention CO that is the major hydrogenation product and butane is formed in much lesser selectivity (in contrast to what the title suggests). I think that isobutane should appear somehow in the title.
Response: Thanks to the reviewer for pointing out this important and very interesting issue.
Due to the intervention from the reverse water-gas shift (RWGS) reaction, the hydrogenation of CO2 into hydrocarbons often displays a rather high selectivity to CO. An ideal solution to this issue is naturally to design a catalyst that is only active to the hydrogenation of CO2 to the defined products but absolutely inactive to the RWGS reaction; this is however rather difficult and may be even impossible in practice.
As pointed out by the reviewer, although current InZrOx-Beta composite catalyst shows a high selectivity to butane in hydrocarbons, a large amount of CO is simultaneously produced in the CO2 hydrogenation process. This is also the common feature of the reported bifunctional catalysts at present for the CO2 hydrogenation to hydrocarbons (Nat. Commun. 2018, 9, 3457;Joule. 2019, 3, 570;ACS Catal. 2019, 9, 3866;Sci. Adv. 2020, 6, eaba5433…). To avoid misleading readers, we further emphasize in the abstract, main text and conclusion that the selectivity to butane was calculated based on total hydrocarbons (CO free), while the formation of CO in the CO2 hydrogenation process was separately evaluated, as described in previous articles (Nat. Chem. 2017, 9, 1019Angew. Chem. Int. Ed. 2021, 60, 17735;Nat. Catal. 2022.
For the hydrogenation of CO2 to hydrocarbons, the reaction results are usually reported in the product selectivity in which the product of CO from the RWGS reaction is excluded. We admit that this will make the reaction results somewhat good-looking; however, this is also the customary way to evaluate the capacity of a catalyst in the CO2 hydrogenation to hydrocarbons, as CO may be considered as an unreacted component and can be recycled for further hydrogenation to hydrocarbons.
Meanwhile, as reported in our previous works (Ind. Eng. Chem. Res. 2022, 61, 17027-17038;J. Fuel Chem. Technol. 2023, 51, 482-491), for the hydrogenation of CO2, although the RWGS reaction may have a severe influence on the equilibrium conversion of CO2 as well as the equilibrium selectivity to CO, it only has a relatively minor impact on the C-based equilibrium yield of the target hydrocarbon product under appropriate reaction temperatures and pressures. Moreover, the reaction tail gas after extracting the target product, which is surely a mixture of CO and CO2, is also credible for the production of hydrocarbons in practice through hydrogenation.
As we mentioned in a previous work (J. Fuel Chem. Technol. 2023, 51, 482-491), the mixture of CO and CO2 is practical and may be even more efficient and cost-effective to produce hydrocarbons from CO2 through hydrogenation, in comparison with pure CO2, where the overall C-based yield should be used as the major index to evaluate such reaction processes. Naturally, this will need to devote great effort in the design and development of efficient catalysts that are highly active for the hydrogenation of both CO and CO2 to the target hydrocarbon products rather than in the possibly hopeless obstruction of the WGS/RWGS reaction. Nevertheless, this is really far beyond the scope of current work.
In addition, iso-butane accounts for more than 86% of two butane isomers for the CO2 hydrogenation over current InZrOx-Beta composite catalyst (Page 12). Therefore, following the reviewer's suggestion, the Title of the revised manuscript was further modified to "Selective Conversion of CO2 to Isobutane-enriched C4 alkanes over InZrOx-Beta Composite Catalyst".
Thanks for the valuable suggestions. Taking the reviewer's concern into account, above points were strengthened in the revised manuscript (Pages 12-13). Response: Thanks to the reviewer for pointing out this very important issue. We did pay more attention on the minor peak in the H2-TPR profiles, just because the intensity of such minor peak at a lower temperature is more closely related to the catalytic performance of InZrOx-Beta composite in the CO2 hydrogenation.
In the H2-TPR profiles, the peak at around 150-250 °C is attributed to the reduction of defect In2O3 sites to In2O3−x, whereas that centered at 650 °C corresponds to the reduction of bulk In2O3 to metallic indium (ACS Catal. 2020, 10, 1133Angew. Chem. Int. Ed. 2016, 55, 6261).
It can be seen that the reduction peak at around 150-250 °C of InZrOx(CP) is more intense than that of InZrOx(SG) and InZrOx(HT), along with certain shift towards a lower temperature. This is indicative of the presence of more surface defects or oxygen vacancies in the InZrOx(CP) after H2 reduction, in a good agreement with the in situ XRD Rietveld refinement ( Fig. 2c in main text and Supplementary Fig. 7) and the in situ O 1s XPS deconvolution results ( Supplementary Fig. 6).
As stated in the manuscript, the catalyst samples were reduced at 400 °C and used in the CO2 hydrogenation reaction at about 315 °C. In the H2-TPR profiles, the low-temperature reduction peak is related to the reduction of defect In2O3 sites to In2O3−x, which are considered to be responsible for the adsorption and activation of CO2. In contrast, the intense peak at about 650 °C attributed to the reduction of bulk In2O3 to metallic indium species was less relevant to the catalytic performance of InZrOx-Beta in the CO2 hydrogenation.
Nevertheless, as pointed out by the reviewer, the onset temperature for the reduction of bulk In2O3 to metallic indium species is only around 315 °C. It is then conceivable that certain metallic indium species may be generated on the surface of InZrOx oxide during the reduction and subsequent reaction processes. These metallic indium species may easily migrate to the zeolite moiety and then poison the acid sites of zeolite component (Angew. Chem. Int. Ed. 2021, 60, 17735;J. Catal. 2022, 413, 923). This is confirmed by observing Thanks really for the valuable comments. Considering the reviewer's concern, these relevant descriptions about the H2-TPR profiles have been supplemented and above points were strengthened in the revised manuscript (Page 9).

Q3: The influence of H2O in the process should be addressed by adding various proportions in the feed.
Response: Thanks to the reviewer for the constructive suggestion. Following this suggestion, the role of water during the CO2 hydrogenation was further analyzed in the revised manuscript by adding different proportions of water into the H2 and CO2 feed (Pages 12-13;

Supplementary Figs. 11-15 and Supplementary Table 3), like:
"As water is a co-product in the hydrogenation of CO2, which acts also vividly in the competitive reverse water-gas (RWGS) reaction (Ind. Eng. Chem. Res. 2022, 61, 17027-17038;J. Fuel Chem. Technol. 2023, 51, 482-491), the possible role of water in the reaction process was further evaluated by adding different proportions of water into the H2 and CO2 feed. As shown in Supplementary Fig. 11a, when water is introduced into the reaction system after about 16 h, the CO2 conversion decreases from 19.1% to 8.9%, along with the attenuation of the selectivity to CO from 54.7% to 34.0%. Such a phenomenon becomes more evident when the proportion of water in the feed increases from 7.5% to 15.1% ( Supplementary Fig. 11b), where the CO2 conversion and selectivity to CO decreases considerably to 7.3% and 26.1%, respectively. This can be explained by the fact that more water in the reaction mixture can effectively counteract the RWGS reaction (CO2 + H2 = CO + H2O), leading to the decline of the CO2 conversion and the selectivity to CO (ACS Catal. 2020, 10, 8303;Chem. Commun. 2020, 56, 5239). In addition, water molecules may also compete for the active adsorption sites with the reactants, which may also abate the conversion of CO2 to hydrocarbons. "It is noteworthy that the conversion of CO2 and selectivity to CO are both spontaneously rejuvenated, when the co-feeding water is cut off ( Supplementary Fig. 11c). However, the CO2 conversion cannot be fully recovered to the original value, implying that co-feeding water has certain impact on the catalytic activity of the InZrOx oxide. The XRD patterns and TEM images of the spent catalysts shown in Supplementary Fig. 12 indicate that after the CO2 hydrogenation with co-feeding water, the particle size of InZrOx oxide increases considerably, along with the decrease of surface area and pore volume (Supplementary Fig.   13a and Supplementary Table 3). This leads to a decrease in the surface oxygen vacancies concentration, which can weaken the CO2 adsorption capacity, as indicated by the O 1s XPS and CO2-TPD results ( Supplementary Fig. 13b-c), although the In, Zr and O elements are still uniformly dispersed with each other in the InZrOx oxide ( Supplementary Fig. 14).   "Nevertheless, the selectivity to butane changes very little during the reaction. This is ascribed to the fact that the crystal structure, morphology, and particle size of H-Beta zeolite, which determine the manner for the formation of hydrocarbons from the methanol-related intermediates, are well maintained during the CO2 hydrogenation with co-feeding different contents of water ( Supplementary Fig. 15). Table 3. Textural properties of the spent InZrOx(CP) oxides after conducting the CO2 hydrogenation reaction with co-feeding different contents of water.
Thanks really for the valuable comments. Considering the reviewer's concern, these relevant descriptions and discussion have been supplemented in the revised manuscript and above points were strengthened (Pages 12-13; Supplementary Figs. 11-15 and Supplementary   (40)  Response: Thanks to the reviewer for pointing out this important and very interesting issue.
In the revised manuscript, with the help of valuable hints from the reviewer's comment, this part of work was modified greatly (Pages 21-30), like: "The degeneration of either the metal oxide moiety or the zeotype moiety can deactivate the whole bifunctional OX-ZEO catalyst system in the hydrogenation of CO2 to hydrocarbons.
The degeneration of metal oxide often causes a rapid decrease in the CO2 conversion, as the adsorption and activation of CO2 are mainly performed on the surface of metal oxide. As for the acidic zeolite, it catalyzes the subsequent transformation of the methanol-related intermediates previously generated on the oxide moiety into hydrocarbons; the rapid increase in the selectivity to unconverted methanol is an important sign for the deactivation of the zeolite component. For the In-based bifunctional catalyst, the indium species may facilely migrate from the oxide moiety into the zeotype moiety in the H2-containing atmosphere, which can passivate the acid sites in the zeotype moiety and then rapidly deactivate the whole composite catalyst used in the CO2 hydrogenation by lowering capacity of the acidic zeolite component in the transformation of methanol-related intermediates to hydrocarbons." "To improve the structural stability of the In-based catalyst in the CO2 hydrogenation, a surface silica protection strategy was adopted in current work; that is, certain amount of SiO2 (4 wt.% for InZrOx(SCP-4) and 8 wt.% for InZrOx(SCP-8)) was deposited on the InZrOx(CP) oxide through impregnation with tetraethylorthosilicate (TEOS) solution and subsequent calcination at 500 °C (Supplementary Fig 21a). The XRD patterns shown in Fig. 9a indicate that the surface silica modification has little impact on the crystal structure of InZrOx(CP). In addition, no diffraction peaks of SiO2 are detected, suggesting that SiO2 is highly dispersed on the InZrOx surface and/or present in amorphous phase. The EDX elemental mapping results show that the silica species are evenly distributed on the surface of InZrOx(CP), despite that they cannot be clearly distinguished by XRD, HR-TEM and Aberration-corrected HAADF-STEM ( Fig. 9a and Supplementary Figs. 22-24), which consolidates the high dispersion of silica in the SiO2-modified InZrOx oxide.  Table 5). Besides, the SiO2-modified InZrOx(SCP-4) and InZrOx(SCP-8) oxides have the average particle size of 6.10 and 4.70 nm, respectively, much smaller than 13 that of the unmodified InZrOx (9.76 nm) ( Supplementary Fig. 26), suggesting that the silica modification can also inhibit the agglomeration of InZrOx upon calcination at high temperature.  Thanks really to the reviewer for the valuable comments. Considering the reviewer's concern, these relevant descriptions and discussion have been supplemented and above points were strengthened in the revised manuscript (Pages 21-30; Supplementary Figs.

Q6: It is proposed that the authors use silica-coated InZrOx and determine the relocation of In on the silica layer under reaction conditions over the time on stream. Should it not the In environment change from Zr to Si over the time? Why this change does not affect to the hydrogenation performance of the catalyst? What would be the performance and stability of an InSiOx phase?
Response: Thanks to the reviewer for pointing out this very important and interesting issue.
We are very sorry for the misunderstanding caused to the reviewer due to the unclear description of the surface silica protection mechanism in the old version manuscript. As responded to the Query Q5, with the help of these valuable hints from the reviewer's constructive comments, this part of work was modified greatly in the revised manuscript (Pages 21-30), like: "It is noteworthy that although the strong interaction between the surface SiO2 species and InZrOx oxide can inhibit the indium species from easy reduction and migration and then improve the stability of the InZrOx-Beta composite catalyst in the CO2 hydrogenation, it does not relocate the indium species on the composite catalyst. In other words, the silica species are only highly dispersed on the surface of InZrOx oxide and do not cause any significant structural distortion and/or rearrangement of the InZrOx oxide upon the reduction and reaction process over the time. and InZrOx(SCP-4)-42h samples are all highly comparable to those of the fresh counterpart ( Supplementary Fig. 39j-l and Supplementary Fig. 40a). In addition, the TEM images display that the particle size of InZrOx(SCP-4) is only slightly increased from 6.10 nm of fresh InZrOx(SCP-4) to 6.89 nm of InZrOx(SCP-4)-24h and to 7.30 nm of InZrOx(SCP-4)-42h ( Supplementary Fig. 39a-i). Meanwhile, the surface In/Zr and In/Si ratios of InZrOx(SCP-4) also show little change upon the CO2 hydrogenation reaction test ( Supplementary Fig. 40b-e). That is, the major function of the introduced surface silica species is the inhibition of the indium species from reduction and migration in the reductive atmosphere containing hydrogen, whereas without causing any significant structural distortion and atomic rearrangement of the InZrOx oxide as well as the InZrOx-Beta composite catalyst upon the preparation and reaction process over the time. Moreover, following the reviewer's suggestion, such a strategy can also be extended to the SiO2-modified In2O3-Beta catalyst. As shown in Supplementary Fig. 38a, the In2O3(SCP-4)-Beta(40) catalyst shows a long catalytic lifetime (ca. 65 h) and high selectivity to butane (ca. 53% in hydrocarbons) in the CO2 hydrogenation. In contrast, over the unmodified In2O3(CP)-Beta(40) counterpart, the selectivity to butane is quickly decreased to 30%, along with the generation of much more unconverted methanol (25%) after reaction for ca. 65 h (Supplementary Fig. 38b). Undoubtedly, the improved stability of the In2O3(SCP-4)-Beta(40) catalyst also originates from the inhibition of the indium species from reduction and migration by the surface silica protection, which can alleviate the rapid deactivation of the zeolite moiety in the hydrogenation of CO2 to hydrocarbons ( Supplementary Fig. 38c-e).
Thanks again to the reviewer for the valuable comments. Considering the reviewer's concern, these relevant descriptions and discussion have been supplemented and above points were strengthened in the revised manuscript (Pages 21-30).
Q7: Figure S15 and Figs. 16A and 17A should be improved to present more clearly the silica overlayer on InZrOx. Particle size distribution in Fig. S19 is difficult to be seen.

Response:
Thanks really for raising these matters present in the old version manuscript. Considering the reviewer's suggestion, the morphology and structure of silica-modified InZrOx(SCP-4) and InZrOx(SCP-8) were further investigated by Aberration-corrected HAADF-STEM. As shown in Supplementary Fig. 22, no evident silica overlayer is observed even in the high resolution Aberration-corrected HAADF-STEM images, indicating that these silica species are amorphous and evenly dispersed on the surface of InZrOx(SCP-4) and InZrOx .
This is also supported by the EDX elemental mapping that Si, In, Zr and O elements are uniformly dispersed with each other over these two samples (Supplementary Figs. 23 and 24). Moreover, the HR-TEM images show that the lattice spacing of 0.290 nm for the (222) crystal facet of In2O3 extend to the edge of catalyst, whereas the nonmetallic layer (e.g. silica overlayer) is undetectable ( Supplementary Fig. 22). Moreover, according to the reviewer's suggestion, the TEM images and corresponding particle size distributions of the InZrOx(SCP-4) and InZrOx(SCP-8) samples were further improved to make them clearer ( Supplementary Fig. 26). It is noteworthy that the silica layer deposited on InZrOx may also cover a fraction of the surface oxygen vacancies and then has certain impact on the adsorption and activation of H2 and CO2 on the catalyst surface. Although the increase of the SiO2 loading is favorable for lowering the impact of indium migration on the butane formation, it also leads to a decrease of CO2 adsorption capacity on the SiO2-modified InZrOx oxides ( Supplementary Fig. 30). As shown by the O 1s XPS spectra in Supplementary Fig. 31, InZrOx(SCP-4) and InZrOx(SCP-8) have a lower concentration of surface oxygen vacancies but abundant OH groups originated from the surface Si-OH of SiO2, in comparison with the InZrOx(CP) counterpart.
Accordingly, the loading of SiO2 for the surface protection of the InZrOx oxide should be restricted to a certain value (ca. 4-8 wt.%) to elevate the catalytic stability of catalyst and meanwhile avoid a substantial decrease of the CO2 conversion.  Thanks again to the reviewer for the valuable suggestions. Considering the reviewer's concern, all of these descriptions and improvement have been embodied in the revised manuscript and above points were strengthened in the revised manuscript (Pages 21-30). All these results reveal that the surface silica protection strategy used in current work is rather effective in suppressing the phase segregation of InZrOx oxide moiety and avoiding the rapid poisoning of the acid sites in thezeolite moiety induced by the In migration, which can thus significantly improve the structural and catalytic stability of the In-based oxide-zeolite composite catalyst in the CO2 hydrogenation.  We do agree with the reviewer's opinion that the absence of XRD diffraction peaks of SiO2 species does not fully prove its dispersion, as these SiO2 species may be amorphous phase. Therefore, the Aberration-corrected HAADF-STEM and corresponding EDX elemental mapping were further carried out; the results indicate that these amorphous silica species are evenly dispersed on the surface of InZrOx oxide . Accordingly, these relevant descriptions have been supplemented in the revised manuscript (Pages 23-24) like: We are sorry for not providing a clear definition and clarification in the old manuscript on the stability of the bifunctional InZrOx-Beta composite catalyst in the CO2 hydrogenation to hydrocarbons.
As responded to previous Query Q5, the degeneration of either the metal oxide moiety or the zeotype moiety can deactivate the whole bifunctional OX-ZEO catalyst system in the hydrogenation of CO2 to hydrocarbons (Chem. Soc. Rev. 2019, 48, 3193;ACS Catal. 2019, 9, 3026). The degeneration of metal oxide often causes a rapid decrease in the CO2 conversion, as the adsorption and activation of CO2 are mainly performed on the surface of metal oxide (Nat. Chem. 2017, 9, 1019ACS Catal. 2020, 10, 1133. As for the acidic zeolite, it catalyzes the transformation of the methanol-related intermediates previously generated on the oxide moiety into hydrocarbons; the rapid increase in the selectivity to unconverted methanol is an important sign for the deactivation of the zeolite component (Nat. Commun. 2019,10, 1297Angew. Chem. Int. Ed. 2021, 60, 17735;ACS Catal. 2021, 11, 9729). For the In-based bifunctional catalyst, the indium species may facilely migrate from the oxide moiety into the zeotype moiety in the H2-containing atmosphere, which can passivate the acid sites in the zeotype moiety and then rapidly deactivate the whole composite catalyst used in the CO2 hydrogenation by lowering capacity of the acidic zeolite component in the transformation of methanol-related intermediates to hydrocarbons." (Angew. Chem. Int. Ed. 2021, 60, 17735;J. Catal. 2022, 413, 923) In this work, the gradual increase of the selectivity to unconverted methanol reveals that the deactivation of InZrOx-Beta bifunctional catalyst is mainly ascribed to the passivation of the acid sites in the H-Beta zeolite, although the CO2 conversion is relative stable with the reaction time. Herein, the catalytic lifetime of the bifunctional InZrOx-Beta composite catalyst was defined as the reaction time when the selectivity to unconverted methanol was increased to 2%.
As shown in Fig. 8b and Supplementary Fig. 28a  these relevant descriptions and discussion have been supplemented and above points were strengthened in the revised manuscript (Pages 26-28).

Q10: If the authors address satisfactorily the previous points, publication would be recommended.
Response: Thanks again to the reviewer for the very positive comments as well as the informative and instructive revision advices. With the help of these advices, the revised manuscript was improved greatly. In audition, as the reviewer can see, all the raised issues have been carefully and pertinently addressed. In particular, more characterizations about the used InZrOx oxide and H-Beta zeolite have been provided. The dispersion of silica species on the surface of InZrOx oxide was further evaluated by Aberration-corrected HAADF-STEM images, HR-TEM images and EDX-elemental mapping. The influence of co-feeding water on the catalytic performance and the surface silica protection mechanism were systemically investigated. Moreover, the interaction between the surface silica species and InZrOx oxide and its relation to the catalytic stability of InZrOx-Beta in the CO2 hydrogenation have been well clarified.
We hope that our revision work is satisfactory to the reviewer and the acceptance of this manuscript for publication can be approved.

Thanks to the reviewers for the informative and constructive advices and kind efforts in
handling this manuscript. As the reviewers can see, with the help of these advices, the revised manuscript was improved greatly; we would be very grateful if the acceptance of the revised manuscript can be approved.

REVIEWERS' COMMENTS
Reviewer #1 (Remarks to the Author): The authors have satisfactorily addressed the reviewers' comments and improved the quality of this paper. I would recommend accepting it.